I haven't done RAID yet, but from what I know, if you have a RAID 0 config between two drives and you disconnect them it won't work. RAID 0 splits your files in two basically with its parity, which is the reason why it's called the performance RAID and not a true redundancy RAID.
If you do separate, you'll still have the files on them but they'll be corrupted since they'll be missing its other half.
But to have two drives with identical files on them, RAID 5 is the solution. It makes a mirror copy basically of two drives, so when one dies, you can plug a new identical drive in and it'll rebuild itself. Technology is crazy isn't it!